Personality tests measure the default settings of your motivational system. The motivational system drives your actions, and those settings affect what you find easiest and most natural to do. For example, people who are high in the personality characteristic of conscientiousness like structure and rules, and are motivated to complete the tasks that they start. People low in conscientiousness are not as strongly driven to complete what they start and are not as deeply tied to the rules that govern a situation.

It is important to recognize that the particular behavior a person will exhibit in a situation is a reflection both of those default settings of their motivational system as well as the motivations that are created by the particular situation that person is in. Often, situational forces are strong enough to lead people to act in ways that might seem surprising, given their personality characteristics. Even a person who is not that conscientious may buckle down to complete a task if there is a big reward for completing it or a significant punishment for failure.

Even a person who is not that conscientious may complete a task if there is a big reward for completing it or a significant punishment for failure.

In fact, situations are so powerful that when personality psychologists measure the influence of particular personality characteristics on behavior, those characteristics tend to account for, at most, 20% of the difference in performance between people. Of course, other personality characteristics are also affecting behavior. But much of the way someone acts in a situation is a reflection of the situation and the habits people have developed rather than their personality.

As one final note in this mix, because personality influences both what people find easiest and most natural to do, they tend to gravitate to situations that fit their personality. But the workplace often puts people in situations that are not a good fit for their default modes of interacting with the world. In those cases, they may feel a little uncomfortable, but they will still act in ways that are appropriate for the situation.

All of this means that the results of personality tests need to be treated with some care. Personality is not destiny. Just because you have a particular personality characteristic does not mean that you are guaranteed to act in a specific way. In addition, you can always develop habits that allow you to act naturally in ways that counteract the settings on your motivational system.

On the one hand, this means that there is some value in trying to match people to jobs that fit their personality characteristics. That fit will allow people to use their natural inclinations in ways that will benefit their job performance. But because personality is ultimately one factor that motivates people to act, you must also take other factors into account when making employment decisions.

Much of the way someone acts in a situation is a reflection of the situation and the habits people have developed rather than their personality.

A person who expresses a strong desire to take on a particular role is likely to learn new skills and habits that will allow them to succeed in that role, even if their personality characteristics would suggest they are not well-suited to that job. That internal motivation to succeed is often a stronger force than the motivation provided by personality characteristics.

Ultimately, it is useful to treat personality a little like intelligence. Most tests of intelligence focus on broad abstract mental capacities like working memory (how much information you can keep in mind at once) or logical reasoning. Intelligence affects how easily you can learn new things and can solve new problems. But the knowledge you have and your ability to use that knowledge is a much better predictor of your effectiveness in a particular domain than your intelligence. I think of myself as a smart person, but I don’t know how my car works, and I am useless when it comes to fixing it.

Personality is the same. It has its biggest impact when a person has no habits or skills that relate to a situation, and when the situation itself does not strongly constrain people’s behavior. When people do have skills and habits, or the situation guides everyone’s behavior, then their personality matters less.

Personality inventories can be a valuable tool for understanding yourself and the people you work with. But it is important to put them in context. Don’t let them take on a life of their own.

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